1. Field of the Invention
The present invention relates to a quick coupler for the removable join of pipes conveying fluid under pressure.
2. Brief Description of the Related Art
Patent FR-2 514 855 discloses a quick coupler which comprises two elements, male and female, adapted to fit axially, provoking the opening of a closure valve mounted in the body of the female element, this body being equipped with a loaded latch or button, mounted to slide in this body and pierced with a central opening for fit of the male element. The wall of the opening of the latch presents teeth offset with respect to one another along a median axis of this opening, while the male element is provided with a shoulder adapted to rest selectively against one or the other of these teeth. When the coupler is in configuration for passage of fluid, a first tooth of the latch maintains the male element in place in the female element. When the coupler is unlocked, the latch is displaced in order to release the male element which then comes into abutment on that tooth of the latch nearest the opening of the female element.
This conventional arrangement is satisfactory from the standpoint of robustness and reliability.
However, a powerful spring must be used for elastically loading the latch towards a position in which it retains the male element, which may prove awkward when the latch is being manipulated and when the coupler is being coupled, as the effort generated by the spring must be overcome in order to allow the introduction of the male element in the female element.
In addition, Patents FR-2 724 710 or U.S. Pat. No. 5,806,832 disclose a quick coupler comprising a female element in which a male element is inserted. A latch provided on the female element comprises a catching member associated with balls engaging in a groove of the male element in order to maintain these elements in position of coupling. When, by a movement of translation of the latch, the catching member is disengaged from the groove in order to uncouple these elements, a safety device maintains the balls in position as long as the pressure exerted by the fluid inside the pipes is high. This safety device comprises a piston subjected, on the one hand, to the action of a return spring, and, on the other hand, to the effect of the pressure exerted by the fluid circulating in the coupler. These two actions are antagonistic and have the effect of maintaining the piston in a position where it makes it possible to immobilize the male element thanks to the balls as long as the internal pressure remains high.
However, such a coupler presents drawbacks:
In order to ensure that the pressure on one side of the piston is higher than the pressure on the other side, the piston must be equipped with two sealing rings which brake its displacement and oppose the action of the spring. This may disturb the functioning of the coupler.
It is a particular object of the present invention to overcome these drawbacks by proposing a coupler between pipes conveying fluids under pressure, which can be uncoupled in complete safety when the pressure inside the male element is low.